// 需求：防止按钮在短时间内被多次点击，使用节流函数限制规定时间内只能点击一次。
//
// 思路：
//   1、第一次点击，立即调用方法并禁用按钮，等延迟结束再次激活按钮
//   2、将需要触发的方法绑定在指令上
//
// 使用：给 Dom 加上 v-throttle 及回调函数即可
// <button v-throttle="debounceClick">节流提交</button>

import type { Directive, DirectiveBinding } from 'vue'

interface ElType extends HTMLElement {
  __handleClick__: () => any
  disabled: boolean
}
const throttle: Directive = {
  mounted(el: ElType, binding: DirectiveBinding) {
    if (typeof binding.value !== 'function')
      throw new Error('v-throttle: Binding value must be a function.')

    let timer: NodeJS.Timeout | null = null
    el.__handleClick__ = function () {
      if (timer)
        clearTimeout(timer)

      if (!el.disabled) {
        el.disabled = true
        binding.value()
        timer = setTimeout(() => {
          el.disabled = false
        }, 1000)
      }
    }
    el.addEventListener('click', el.__handleClick__)
  },
  beforeUnmount(el: ElType) {
    el.removeEventListener('click', el.__handleClick__)
  },
}

export default throttle
